Section 221.3 - Application(a) Except as provided in paragraph (b) of this section, this part applies to passenger, commuter and freight trains when operated on a standard gage main track which is part of the general railroad system of transportation.(b) This part does not apply to:(1) A railroad that operates only trains consisting of historical or antiquated equipment for excursion, educational, or recreational purposes;(2) A train that operates only on track inside an installation which is not part of the general railroad system of transportation;(3) Rapid transit operations in an urban area that are not connected with the general railroad system of transportation.(4) A railroad that operates only one train at any given time.42 FR 2321, Jan. 11, 1977, as amended at 53 FR 28600, July 28, 1988